Caption: Diving bell spider (Argyroneta aquatica) carrying air to its diving bell. The diving bell is created from a web silk-lined air bubble, which the spider inflates by trapping air at the surface and carrying it down to the bubble. Once established, the diving bell provides the spider with a home, from which it darts out to catch nearby prey. Oxygen naturally diffuses into the bubble from the surrounding water, with carbon dioxide diffusing the other way. The diving bell spider is the only fully aquatic spider, and inhabits fresh water throughout Europe and northern Asia.